init: stdlib app-entry-point logging setup (live run.log, rotation, gzip, retention)

Signed-off-by: disqualifier <dev@disqualifier.me>

.gitignore

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+# claude
+CLAUDE.md
+
+# python
+__pycache__/
+*.py[cod]
+*.egg-info/
+dist/
+build/
+.eggs/
+
+# env
+.venv/
+venv/
+.env
+.pytest_cache/

README.md

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+# log_setup
+
+Stdlib, sync, **zero-dependency** logging setup an application calls **once** at its
+entry point: a live `run.log`, rotation (daily / size / on-start), gzip of rolled
+files, retention, console output, and a consistent `time | module | level | message`
+format.
+
+It **configures** logging (handlers, rotation, format) — which reusable libraries here
+must never do. That's fine because `log_setup` is the *application's* entry-point
+setup, not library-internal config. Libraries still only `logging.getLogger(__name__)`
+and emit; their records flow into the handlers `log_setup` wired.
+
+## Install
+
+```
+log_setup @ git+ssh://git@git.rethinkstudios.io/rethink-public/log_setup.git@v0.1.0
+```
+
+No dependencies — stdlib only.
+
+## Quick start
+
+```python
+import logging
+from log_setup import setup_logging
+
+setup_logging(name="run", level="INFO")     # daily rotation, logs/ dir, gzip (file only)
+
+log = logging.getLogger(__name__)
+log.info("started")                          # -> ./run.log  (add console=True for stdout too)
+```
+
+Call it once, at the app's entry point — before the rest of the app runs. Every module
+(yours and the libraries you import) then just does `logging.getLogger(__name__)` and
+emits; the records land in the configured root.
+
+## What you get
+
+- **Live file** at a stable path: `./run.log` — always `tail -f run.log`, no dated name
+  to chase. Rolled/compressed copies go into `log_dir` (default `logs/`).
+- **Format:** `2026-06-27 19:55:05 | module.name | INFO | message`. `%(name)s` is the
+  `getLogger` name each module used, so you see which lib/module logged.
+- **Rotation** (`rotate=`):
+  - `"daily"` (default) — rolls at midnight, dated name into `log_dir`, keeps
+    `backup_count` days.
+  - `"size"` — rolls at `max_bytes`, numbered backups in `log_dir`.
+  - `"on_start"` — on startup, moves an existing `run.log` into `log_dir`
+    (`run.<timestamp>.log[.gz]`) and starts fresh; prunes to `backup_count`.
+  - `None` — single file, no rotation.
+- **compress=True** (default) gzips each rolled file (`run.log.2026-06-27.gz`).
+- **Retention** = `backup_count` (default 14) for every mode.
+- **console=True** (off by default) also logs to stdout in the same format — opt in when
+  you want live terminal output alongside the file.
+
+## Signature
+
+```python
+setup_logging(
+    name="run",               # base -> run.log (the live file at cwd)
+    log_dir="logs",           # rotated/compressed copies live here (created if absent)
+    level="INFO",             # root level (str name or logging constant)
+    rotate="daily",           # "daily" | "size" | "on_start" | None
+    backup_count=14,          # rotated files to keep (older auto-deleted)
+    max_bytes=10_000_000,     # only for rotate="size"
+    compress=True,            # gzip rolled files
+    console=False,            # also log to stdout (off by default; opt in)
+    queue=False,              # route through a background QueueListener (async-friendly)
+    fmt=None,                 # override the format string
+    datefmt=None,             # override the date format
+) -> logging.Logger           # returns the configured root logger
+```
+
+## Async-friendly (`queue=True`)
+
+For async-heavy apps, `queue=True` routes records through a stdlib `QueueHandler` to a
+background `QueueListener` that owns the file/console handlers, so the event loop never
+blocks on file I/O. The API stays sync (`log.info()` as usual); the queue is internal.
+The listener is stopped (and flushed) cleanly at process exit, so no records are lost.
+
+```python
+setup_logging(name="run", queue=True)
+```
+
+## Safety
+
+- **Idempotent:** calling `setup_logging` again clears only the handlers it added (no
+  duplicate lines) and leaves handlers your app added itself alone.
+- **Never crashes the app over logging:** if `log_dir` isn't writable, it falls back to
+  console-only with a warning instead of raising.
+
+## Scope — what this is NOT
+
+`log_setup` produces clean, rotating, compressed, retention-managed, consistently
+formatted **files**. It does **not** ship logs anywhere — no Loki/ELK/syslog/network
+handlers. Getting files to a backend is a separate concern (e.g. Promtail tails
+`run.log` → Loki → Grafana panels + alerting). Keeping shipping out means the log
+backend can change without touching any app, and the consistent format here is what
+makes downstream parsing and alerting easy.
+
+Also out of v0.1.0 (possible later additions): structured/JSON logging, color
+formatting, per-logger filters, remote handlers.
+
+## Versioning
+
+Tagged `vX.Y.Z`. Pin the tag.